Various herbicidal compositions have been studied to control undesired plants (hereinafter simply referred to as weeds) in agricultural fields and non-crop land. For example, Patent Document 1 discloses a mixture comprising a sulfonylurea herbicide, diuron and hexadinone. However, Patent Document 1 failed to specifically disclose a synergistic herbicidal composition comprising compounds A and B. Further, Non-Patent Document 1 discloses influences over cultivation of sugarcane by mixed use of flazasulfuron and diuron. However, Non-Patent Document 1 failed to disclose whether a synergistic herbicidal effect is obtained when they are used in combination.